A turbocharger may include a center housing disposed between a compressor housing and a turbine housing where the center housing supports a bearing or bearings for rotation of turbocharger shaft operatively coupled to a turbine wheel housed by the turbine housing and a compressor wheel housed by the compressor housing. In operation, such a turbocharger can extract energy from the flow of high temperature exhaust from an internal combustion engine to compress intake air for the internal combustion engine.
As an example, a center housing may be formed as a unitary piece, for example, using a casting process followed by a machining process. A casting process may involve providing an assembled multi-piece core about which a center housing is cast using a mold (e.g., a cast). In such an example, the mold may be formed from compacted sand contained in a mold box where the compacted sand forms the outer surfaces of a component shape. As an example, a core may be positioned in a mold (e.g., within a shape formed by the compacted sand). To form a cast component, a mold may be filled with material such as molten metal or alloy, which may flow to spaces between compacted sand and a core, if present. After hardening of the fill material, a mold box may be opened and the compacted sand removed to reveal the cast component. Where a core is present, it may then be removed from the cast component, for example, as part of a de-coring process. Various issues exist for center housings formed as a unitary piece by casting. For example, debris may be trapped in regions difficult to access or inspect (e.g., regions formed via the core). Machining may also be complicated or otherwise limited, especially as to regions formed using a core or cores. Such manufacturing related issues may have an impact on turbocharger operation.
Various aspects of turbocharger operation may be affected by temperature. For example, where a bearing or bearings are lubricated by lubricant, high temperatures in a center housing may cause lubricant degradation, coking, deposit formation, etc. As another example, heat soak back from a turbine side to a compressor side can add to the increase in intake air temperature caused by compression, which may correspondingly increase load of a charge air cooler. As to the aforementioned unitary piece center housing, as a result of manufacture, traps may exist that act to collect lubricant where time and temperature may result in coking. Further, being a unitary piece, conduction of heat energy may readily occur from a turbine side to a compressor side of the center housing, which may act to elevate temperature in a bearing and shaft system.
Various examples of turbocharger components, assemblies, etc. are described herein that may, as an example, facilitate manufacture, reduce heat soak back during operation and increase performance.